Scale Calibration Weights

Scale Calibration Weights

  • Consult Us
  • 1(800)-268-3269
Scale Calibration Weights

Scale Calibration Weights

Interweigh Systems supplies cast iron and stainless scale calibration weights and weight sets for verifying mass at a very precise level of accuracy in the laboratory and industrial applications. Our calibration weights meet or exceed all necessary standards including ASTM, OIML, and NIST specifications. We not only provide the highest quality mass calibration service available today, but we also supply weight accessories to maintain your weights in their original pristine condition. These accessories include everything from transfer carts and carrying carts, to canvas dust covers for large weights and gloves and tweezers for handling weights.

For more information on our calibration weights click on the links below:
Precision Laboratory Stainless Steel Weights and Sets.
Stainless Steel or Cast Iron Calibration Industrial Weights and Sets.
Weight Sets and Accessories

Precise and accurate weighing scales are crucial for preserving our quality of life. When you walk into a store to buy some fruit, you want to know that you are getting full value for what you paid for. This depends on the accuracy of the scale used to weigh the fruit and the weight used to keep your scale accurate. This is why most countries and their governments develop standards, and regulations and promote technology for the design and servicing of scales used in commercial transactions. Accurate and precise weighing devices not only enhance productivity and facilitate trade, but they also improve the overall quality of life. Once a scale meets all these criteria it is said to be legal for trade.

Our ISO Scope of Accreditation

Interweigh's ISO/IEC 17025:2005 Certificate of Accreditation and Scope of Accreditation. (These documents are in a word document and pdf format and require Acrobat 4.0 or higher.)


Scale calibration weights, precision weights or whatever you want to call them, are essential for anyone who wants to ensure that their scales are both precise and accurate. Precision and accuracy are the two cornerstones of ensuring that commercial transactions are fair and trustworthy. The science of making sure that scales are precise and accurate is called metrology. It is the science and process of ensuring that measurement meets specified degrees of both accuracy and precision. Accuracy is the correctness of a measurement, i.e., that it closely matches the value being measured. Precision, on the other hand, is how detailed measurement is.

By way of illustration, imagine that you have two Voltmeters, A and B, measuring a voltage source of 1.56678 volts. Voltmeter "A" can only display a reading of 1.56 volts; Voltmeter "B" can display a reading of 1.49992847 volts. Voltmeter "A" is ACCURATE (its measurement is more correct), but not precise; Voltmeter "B" is PRECISE (more detailed), but not accurate.

The Calibration Process

Metrology, then, is the process by which both accuracy and precision of a scale are tested and adjusted for. This is accomplished through a hierarchical system where each scale is compared against an external reference, known as a standard. Each standard is then tested against a higher level (more accurate and precise) standard, which is compared against an even higher standard, and so on. In Canada and United States, the master document describing how scales must be designed, installed, and used for commercial purposes is the NIST Handbook 44. This process of comparison against a standard, and making any necessary adjustments, is commonly referred to as calibration. Detailed records are kept for every scale to ensure traceability, and that the scale met clearly identified specifications for both accuracy and precision in all its operating parameters. This collaboration between the government and scale manufacturers ensures the highest achievable standards possible and guarantees fairness in the marketplace.

Before ordering test weights and weight sets, it is important to consider your application, the environment the test weights will be housed in, what tolerance and type of test weights you need as well as if you need any official documentation. Please use the following questions below to prepare your order. If there is missing information or if you have any questions regarding what you need, please call 800-268-3269. 


  1. Please describe your application and tell us what you need to accomplish with the weight(s) or weight set.
  2. What is the maximum amount of weight you will need at any one time?
  3. What is the minimum amount of weight you will need at any one time?
  4. Do you need something that is custom manufactured?
  5. What is your budget for this project?
  6. Tell us about your environment. Is it:
    1. Indoor/outdoor?
    2. Wet/dry?
    3. Windy/still?
    4. Corrosive, hazardous or explosive?
    5. A clean room?
    6. An environment with biohazard, electrostatic or magnetic conditions to consider?
    7. An environment with other noteworthy conditions? If so, what are they?
  7. Are you replacing an existing weight or weight set?
  8. If the answer to question number 7 is yes:
    1. What do you like/dislike about the existing weights?
    2. What configuration is the existing set?
    3. What style is the existing set?
    4. What laboratory documentation is needed for the existing set?
  9. Does this weight set need to be Legal for Trade?
  10. What other precision services/equipment (recalibration, balances, accessories, static electricity) do you use?

Tolerance/Type of Weights

  1. What tolerance are you looking for?
  2. Is your tolerance driven by the equipment under test, the application, an internal specification, a document or another source? 
  3. What "style" (ASTM, OIML, NIST) is required or preferred? 
  4. What configuration do you need (5-2-2-1, 5-3-2-1)?


  1. Do you need ISO/IEC 17025 laboratory documentation?
  2. If you do not need ISO/IEC 17025 laboratory documentation, do you need traceability to NIST?
  3. Do you need a Calibration Report?

Your existing weights and weight sets should be recertified on a managed periodic basis. The recertification period is determined by a number of factors, including but not necessarily limited to, the environment, frequency of use, demands of the process, quality of the weighing devices in question, age of the weights in question and handling during use.

Recently viewed